Well survey instrument housing

ABSTRACT

A pressure instrument housing to be used in obtaining improved pressure survey recordings in a well bore having corrosive fluids is provided with pressure entry passages and narrow upwardlyextending channels to prevent displacement by gravity separation of corrosion inhibitor fluids contained in the carrier body.

I 3' .L D .1 Q R 397199088 I United States Patent 1 [111 3,719,088

Noble March 6, 1973 [5 WELL SURVEY INSTRUMENT 1,860,777 5 1932 Harrison ..73 1s2 HOUSING 1,955,855 4/1934 2,413,651 12/1946 [75] lnvemorl Ella" Noble, Calgary, Alberta, 2,259,867 10 1941 Webster ..73/300 Canada [73] Assignee: Schlumberger Technology Corpora- 'f f Prim? "on, New York NY Assistant Examiner-Daniel M. Yas1ch Attorney-Ernest R. Archambeau, Jr., John P. Sinnott, 1 1 Flled! Dec-9,1970 Stewart F. Moore, David L. Moseley, Edward M.

Appl. No.: 96,405

US. Cl ..73/43l, 73/152 Int. Cl. ..E2lh 47/00, GOld 11/24 Field of Search ..73/431, 300, 152, 395, 182

References Cited UNITED STATES PATENTS 2/1934 Dunn et a1 ..73/3()0 Roney and William R. Sherman [57] ABSTRACT 4 Claims, 3 Drawing Figures PATENTED 51975 3,719,088

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Euan Nob/e INVENTOR WELL SURVEY INSTRUMENT HOUSING BACKGROUND OF THE INVENTION Well bore pressure surveys are normally performed by lowering a pressure measuring device into the well bore to the desired depth at which the test is to be performed. Characteristically, the survey is initiated by actuating a clock work mechanism which in turn moves a chart for recording ambient pressure changes as a function of time.

Great difficulty is encountered in protecting the pressure recorders used in these surveys in well bores where destructive gases or other corrosive agents are present. Certain oil bearing formation contain highly corrosive gases which are in solution within the borehole fluids and attack equipment used in the well bore. The most troublesome of these is, of course, hydrogen sulfide gas H 8. A significant problem in prior art housings has been that the various inhibitor fluids typically contained in the housings may be displaced by heavier well bore fluids. Particular difficulties have characteristically been encountered in well bores in which high concentrations of hydrates are present. These hydrates, upon forming a corrosive acid, will usually displace the inhibitors from the prior art housings. The higher specific gravity of the well bore fluids allows the hydrates and the H S gases in solution in the well bore fluids to enter the pressure-entry ports and displace through gravity separation the inhibitors contained in the housing. Pressure recording devices or portions to be protected by these inhibitors are thereby exposed to corrosive damage.

It is, therefore, an object of the present invention to provide new and improved pressure survey apparatus for use in a well bore containing corrosive agents of relatively high specific gravities.

With this and other objects in view, the present invention contemplates a new and improved housing for protecting recording apparatus adapted for use in a well bore environment. In one embodiment of the present invention, the pressure entry port through which well bore fluids are communicated with the internal chamber of the housing is formed at one end ofa narrow passageway into such housing which has an angular displacement above a plane normal to the longitudinal axis of the housing sufficient to prevent the heavier fluids in the well bore from entering the chamber in which the recording instrument is contained. In this manner the well bore fluids, by virtue of their higher specific gravities, are prevented from traversing the passageway, thereby insuring that the inhibitor surrounding the instrument is not displaced.

In an alternative embodiment, this result is achieved by providing an access port formed near the bottom of a long passageway extending upwardly substantially the longitudinal extent of the internal chamber within the housing. The installation of this passageway prevents the heavier well bore fluids from entering into the chamber and displacing the inhibitor in the same manner as the angularly displaced passageway of the previously described embodiment.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention both as to its organization and manner of operation together with further objects and advantages thereof may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in elevation of an assembled well pressure survey tool of the present invention suspended by a cable from a surface well head;

FIG. 2 shows one embodiment of the pressure recorder housing; and

FIG. 3 shows a second embodiment of the pressure recorder housing.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a temperature or pressure survey tool 10 is arranged to be threadedly connected to a connecting member or socket 11 which is in turn coupled from the lower end of a suspension cable 12. The tool 10 is suspended from a platform 19 and extends therefrom through a conventional well head 18. The details of the surface equipment form no part of the present invention and are well-known in the prior art. The tool 10 is depicted adjacent to oil bearing formations 13 traversed by the well bore 14, having been lowered to the particular depth at which the pressure survey is to be conducted. Located within the new and improved housing 15 of the tool 10 are conventional Bourdon tube pressure recorders (not shown) such being contained in the interior of the housing. The interior of the housing 15 is placed in pressure communication with the well bore fluids in a particular manner to be hereinafter described in greater detail.

Referring now to FIG. 2, in one embodiment of the housing 15 of the present invention, an elongated body 16 is adapted to be threadedly connected at its upper end 20 to the socket member 11 (not shown in FIG. 2). An elongated cylindrical chamber 21 is formed within the body member 16, such chamber being adapted for carrying one or more typical pressure recorders (not shown) which are immersed in an inhibiting fluid such as Kontol, available from the Tret-O-Lite Corporation of Houston, Texas, or Corban available from the Dowell Corporation of Houston, Texas. Such corrosion inhibitors come in a variety of densities and solubilities and thus may be readily selected by those skilled in the art according to these properties for use in a particular well. A long, constricted fluid passageway or channel 22 extends substantially the length of the fluid-filled chamber 21, such being simultaneously in fluid communication with the inhibitor contained therein and with the well bore fluids. Suitable pressure recording apparatus, for example, one such as found at Page 2853 of the 1968-1969 Composite Catalog of Oil Field Equipment and Services, may be received within the chamber 21 and secured therein at the bottom thereof, or alternatively, suspended from the threaded portion 20 of the housing 16 and extended downwardly into the chamber 21. In the latter arrangement means may be provided for connecting the wireline socket 11 to the pressure recording apparatus in an alternative manner from that discussed above.

FIG. 3 depicts an alternative embodiment of the housing of the present invention in which the pressure recorder housing 30 is comprised of two interconnected members 31 and 32, the lower of which is adapted to contain a pressure recording apparatus and an inhibitor fluid. The upper member 31 is adapted to be threadedly connected to the lower member 32 and forms a cap for the chamber 34 defined within the lower member and is adapted, at its upper end, to be connected to the wireline socket 11 as previously discussed. In this embodiment, the channel which places the interior chamber 34 and the well bore in fluid communication comprises two intersecting, constricted passageways 35 and 36 formed in the body member 31. The first passageway 35 extends vertically or upwardly above the chamber 34 and intersects the second passageway 36 which is angularly displaced sufficiently below a plane normal to the longitudinal axis of the housing 30 to prevent well bore fluids having a relatively large specific gravity from entering into the first passageway and thereby displacing the inhibitor fluid in the chamber.

In the use of the tool 10, as depicted in FIG. I, a suitable inhibitor fluid is introduced into the chamber in the body 15 and completely immerses the pressure recorder. A clock work mechanism employed in the system is actuated either prior to the lowering of the tool to the desired depth or upon reaching such depth. characteristically, recording devices typically utilized comprise a chart which is moved a suitable clock work mechanism which continues to operate throughout the duration of the survey. Ambient pressures are registered on a sensing device such as a Bourdon tube and are reflected as excursions of a pin or stylus transverse of the direction of displacement of the chart. The specific details of the various mechanisms of the pressure recorder form no part of the instant invention.

Where the housing 16 shown in FIG. 2 is being used, the well bore fluids will enter the ports 23 located in the lower portion of the device and be forced up the long vertical passageway 22 until they come into contact with the inhibitor fluid in the chamber 21 to communicate the well bore fluid pressure to the chamber. As can be readily appreciated, the forces of gravity acting upon the heavier well bore fluids act downwardly upon the fluids in the vertical passageway or channel 22 as well as on the standing column of inhibitor fluid located in the chamber 21. Clearly, therefore, the gravity separation effects which have heretofore readily displaced the inhibitor fluids in the pressure recorder housings of the prior art are arrested by the fluid passageway arrangement of the present invention. By making the point of entry of the well bore fluids at one end of an upwardly extending channel, the heavier fluids are prevented from entering the internal chamber and displacing the protective inhibitor.

Where the housing 15 is arranged as shown in FIG. 3, the lower end of the inlet port 36 is located so that the well bore fluids must move upwardly before coming into contact with the inhibitor contained in the passage 35. Here again, as discussed previously, the gravity separation effects are obviated by virtue of the forces exerted downwardly by gravity on the well bore fluids.

In either of the two embodiments of the housing 15 as shown in FIG. 2 and 3, it can readily be appreciated that the lighter inhibitor fluids within the chamber are not displaced by the heavier well bore fluids entering through the ports since the new and improved arrangements of the respective intercommunicating passages require the upward movement of each fluid against gravity before the well bore fluids can enter the recorder chamber. In order that the inhibitor fluid be displaced by well bore fluids of relatively greater specific gravities, a condition would necessarily exist wherein the lighter fluids would also be forced downwardly through the entrance passageway.

Those skilled in the art will, of course, recognize that pressure recorders and other typical well survey instruments may also be arranged so that only the measuring element is enclosed in a liquid-filled chamber and the remainder of the instrument is simply enclosed in a suitable housing coupled to the chamber. For example, some typical pressure recorders are arranged with only the pressure-responsive element enclosed in a liquidfilled housing section and the remainder of the recorder disposed in one or more tandemly-connected housing sections coupled to the liquid-filled section. Thus, it is considered that the present invention is equally applicable to those situations where the entire instrument is to be enclosed in a liquid-filled housing as well as those where only a portion of the instrument (such as its condition-sensing element) is to be enclosed in a liquid-filled housing.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects and therefore the aim in the appended claims is to cover all such changes and modifications that fall within the true spirit and scope of this invention.

What is claimed is:

1. A well bore instrument housing adapted to be disposed in a fluid filled well bore, comprising: a body having a chamber defined therein to receive a measuring instrument with at least a portion thereof submerged below the level ofa protective liquid contained in said chamber; and passage means for providing communication between the exterior of said body and said chamber and to substantially prohibit the admission of well bore fluids into said chamber, said passage means including a channel in said body and having an entrance exterior of said body located below said liquid level and an exit into said chamber located above said liquid level.

2. The instrument housing of claim 1 wherein said channel is constituted by a tubular member connected with said entrance and extending generally upwardly within said chamber to a location above said liquid level.

3. The instrument housing of claim 1 wherein said channel is inclined at an angle upwardly from said exit, and extends to a point in communication with the upper portion of said chamber.

4. A well bore instrument housing adapted to be disposed in a fluid filled well bore, comprising: a body having an enclosed chamber defined therein and adapted to contain a protective liquid of lesser density than the well bore fluids and at least a portion of a measuring instrument which is to be submerged below the liquid level of said protective liquid; and narrow passage means on said body for communicating the pressure of the well bore fluids with said chamber and said measuring instrument, said passage means extending upwardly from an entrance exterior of said body located below said level to an exit into said chamber located above said level to communicate the pressure well bore fluids into said chamber. 5 

1. A well bore instrument housing adapted to be disposed in a fluid filled well bore, comprising: a body having a chamber defined therein to receive a measuring instrument with at least a portion thereof submerged below the level of a protective liquid contained in said chamber; and passage means for providing communication between the exterior of said body and said chamber and to substantially prohibit the admission of well bore fluids into said chamber, said passage means including a channel in said body and having an entrance exterior of said body located below said liquid level and an exit into said chamber located above said liquid level.
 1. A well bore instrument housing adapted to be disposed in a fluid filled well bore, comprising: a body having a chamber defined therein to receive a measuring instrument with at least a portion thereof submerged below the level of a protective liquid contained in said chamber; and passage means for providing communication between the exterior of said body and said chamber and to substantially prohibit the admission of well bore fluids into said chamber, said passage means including a channel in said body and having an entrance exterior of said body located below said liquid level and an exit into said chamber located above said liquid level.
 2. The instrument housing of claim 1 wherein said channel is constituted by a tubular member connected with said entrance and extending generally upwardly within said chamber to a location above said liquid level.
 3. The instrument housing of claim 1 wherein said channel is inclined at an angle upwardly from said exit, and extends to a point in communication with the upper portion of said chamber. 